Liquid suction systems are employed in a variety of settings and for a variety of purposes. One example is the liquid suction systems which are used for swimming pools, spas and the like. Such system typically includes a suction pump away from the pool for drawing water from the pool at one or more suction ports located along the pool sidewall and/or through the main drain of the pool. A hose is typically connected to one of the sidewall ports and extends to an automatic swimming pool cleaner which draws pool water for cleaning purposes.
Typically, one or more valve mechanisms are used to determine whether water will be sucked from the pool through the main drain and/or through the side port(s). One example of such valve mechanisms is the three-way rotary-plug valve disclosed in U.S. Pat. No. 4,470,429 (Johnson). Such device is a manually-operated rotary-plug valve.
Valve mechanisms of the prior art for controlling which lines will be open to vacuum forces, such as the rotary-plug valve of the aforementioned Johnson patent, have various shortcomings. Among these are the fact that they require manual operation, and thus fail to address problems associated with unexpected line clogging or blockage. Also, even when operated manually such devices fail to provide any vacuum relief in a line which has been manually shut off because of line blockage. In such cases, it may become necessary to turn off the pump and reopen the line in order to relieve the vacuum force remaining in the line. Furthermore, while such devices can be locked into a predetermined position, such locking requires an additional manual step, beyond merely closing a line.
In swimming pool suction systems, when suction lines become obstructed with debris, damage to the lines and equipment may result if excessive vacuum pressures are not quickly released. Furthermore, a risk of bodily injury may exist if a vacuum or suction device comes into contact with a person. Various bypass devices have been developed to address problems of excessive vacuum due to blockage. One example is the device disclosed in U.S. Pat. No. 4,570,660 (Chauvier).
Our U.S. Pat. Nos. 6,460,564 (Rief et al.) and 6,289,918 (Rief et al.) disclose improvements in such valves. More specifically, these patents disclose automatic valves. The present invention is a further improvement in automatic rotary valves which overcomes many problems and shortcomings of the prior art.